Glass staining method and material



Feb. 26, 1963 P. GREGO ETAL GLASS sTAININc METHOD AND MATERIAL Filed Oct. 4. 1961 7794 Ms /7/ r N INVENTORS Para@ @Reso mvo -Poesnr 6. Howe-1.

United States Patent Oihce GLASS STAINENG WHETHD AND M Peter Grego and Robert G. Howell, Corning, N.Y., as-

signors to Corning Glass Works, Corning, N. a corporation of New York Filed Oct. 4, 1961, Ser. No. 142,966

5 Claims. (Cl. 10G- 34) This invention relates .to an improved method `of staining glass with a combination of silver and at is effecting ions, in a paste coating, and sodium ions, in the surface of a soda-lime glass.

It is a well-known practice 'thermally introthe glass surface in Brieily, the practice involves preparing a homogeneous staining paste that contains, as

We have now discovered that the rate in this copper-silver staining celerated by the presence of a small amount or" a lithium paste. We have further found that tofore considered practical. eries we have found color can be produced m ythe surface of a soda-lime glass at considerably lower h a lower Heretofore, silver-copper staining pastes, adapted to produce amber stains, have usually con-tained approximately equal amounts of silver and copper ions in a la pale yellow or green, as of silver to copper in the paste decreased. Accordingly, Where a light stain was desired, a somewhat lower ratio of silver to copper might be employed.

the ratio .bout 1:10 being quite satisfactory for the production if medium dark am-ber colors. While not generally nec- 3,079,264 Patented Feb. 26, 1963 content, calculated on a mole basis of the total silver the desired addiis mixture may then be manner to provide a homogeneous suspension of the solids, that is the staining paste. It is Iapply the staining paste by spraying over even coating. Alternamen-t time of about one hour,

`and a temperature intermediate the glass annealing yand softness points, above the annealing lower than prior staining temperatures. For example, about 450 C. factory for a commercial soda-lime glass used in incandescent bulb production.

This staining temperature will below the strain be about 30 to 40 C. point of the glass. The terms annealing point, softening point, and strain point (or temperature) are used in accordance with A.S.T.M. definitions of these terms.

appreciably longer times or higher temperatures, atendency for crazing to occur in the glass surface also appears.

The following specific example, described with referkxtired at a temperature of 45 Y taining lithium nitrate, had a medium The pastes were prepared by milling and applied by spraying in accordance with conventional staining practice, the processing conditions being maintained as nearly identical as possible with the two pastes.

Each of the paste-coated groups of bulbs was then C. for a period of ten minutes in a sulfur dioxide atmosphere. Following this the bulbs were cooled and the staining paste residue removed. The bulbs stained with the lithium-free paste had a very pale amber surface coloration. 1n contrast, the bulbs stained with staining paste B, the paste condark amber color that was particularly suitable for display lamp purposes. Spectrophotometric curves were obtained for a representative bulb selected from each lot. These curves are shown in the accompanying drawing. rIlle curve for the bulb stained with staining paste A is indicated with a corresponding A and the curve for the bulb stained with staining paste B is correspondingly identiiied as 13. In the drawing percentage transmittance is plotted for the wave lengths across the visible portion of the spectrum, that is from aboutr400 to about 750 millimicrons. As would be expected, curve B, representing the medium dark amber color, has a considerably lower transmittance than does curve A.

Subsequently, a sutlicient amount of surface glass was removed from a representative bulb of each lot to essentially remove all glass within which ion exchange had '2,779,136

occurred. Chemical analysis ot this removed surface glass indicated that the glass removed from the darker color bulb contained about twice as much silver ion and about tive times as much copper as the lighter stained glass. This indicates a preferential acceleration of copper io-n exchange from the mixed ion paste. However, we have not found any evidence ot acceleration of either copper or silver ion exchange in the absence o the other.

What is claimed is:

1. In a method of exchanging a combination oi silver and copper ions from a staining paste for sodium ions from a glass surface, the improvement which consists in providing a source of lithium ions in the staining paste, the amount ot lithium ions present in the paste being from about 0.5 to about 15 mole percent of the total amount of copper and silver ions in the paste.

2. A method in accordance with claim l wherein the ion exchange is eiected to an elevated temperature below the strain point of the glass and tor a time not exceeding about 30 minutes.

3. A method in accordance with claim 1 wherein the ion exchange is effected at a temperature of about 20 C. below the glass strain point and a staining time of about l0 minutes.

4. An improved glass staining paste containing in combination sources of silver, copper, and lithium ions, the content of lithium ions being from about 0.5 to about 15 of the total content oi silver plus copper ions on a mole basis.

V5. A staining paste in accordance with claim 4 wherein the ratio ot silver to copper ions is about 1:10.

References Cited in the tile of this patent UNITED STATES PATENTS 2,662,035 Levi Dec. 8, 1953 2,662,036 Levi Dec. 8, 1953 2,662,037 Levi Dec. 8, 1953 2,701,215 Kroeck Feb. l, 1955 Hood et al Ian. 29, 1957 

1. IN A METHOD OF EXCHANGING A COMBINATION OF SILVER AND COPPER IONS FROM A STAINING PASTE FOR SODIUM IONS FROM A GLASS SURFACE, THE IMPROVEMENT WHICH CONSISTS IN PROVIDING A SOURCE OF LITHIUM IONS IN THE STAINING PASTE, THE AMOUNT OF LITHIUM IONS PRESENT IN THE PASTE BEING FROM ABOUT 0.5 TO ABOUT 15 MOLE PERCENT TO THE TOTAL AMOUNT OF COPPER AND SILVER IONS IN THE PASTE. 